Heretofore, various types of door closers are known. Generally, such known door closers include a piston and cylinder assembly in which a piston is reciprocally disposed within a cylinder, and having a compression spring interposed between the piston and one end of the cylinder for normally biasing the piston toward a door closing position. A piston rod is connected to the piston wherein the free end of the piston rod is extended beyond the end wall of the cylinder. The free end of the piston rod and the end of the cylinder opposed to the piston rod are suitably connected between a door frame and the associated door so that upon the opening of the door, the piston is rectilinearly displaced within the cylinder, causing the spring to be compressed. The spring, in its compressed state, will normally function to return the door toward its closed position upon the release of the door after the opening thereof.
To prevent or to prohibit the closing of the door upon the release of the door, as is frequently desired, such door closers have been provided with an arresting device slidably disposed on the extended end of the piston rod that is manually positioned by the user to arrest the door from closing. Generally, the commonly known arresting device comprises merely a cantering washer which was slidably disposed on the extended end of the piston rod and required the user to manually position the cantering washer along the piston rod to arrest the door. The arrangement was such that the door, on being arrested, caused the cantering washer to frictionally bind or arrest the movement of the piston rod upon the cantering washer engaging the adjacent end of the cylinder. To disengage the arresting or cantering washer, the user would have to manually shift the cantering washer to a normal position relative to the axis of the piston rod to release the frictional forces arresting the piston rod.
Other, more recent, types of door latching or arresting mechanisms are disclosed in my prior patents, viz., U.S. Pat. Nos. 5,630,248; 5,832,562; 5,842,255. While the known types of arresting mechanisms are functional, efforts to devise door closers with new and improved arresting mechanisms is ongoing.